The invention concerns a MAS (magnetic angle spinning) NMR (nuclear magnetic resonance) apparatus, in particular an HR (high resolution) MAS-NMR apparatus, with automatic sample supply by a supply unit.
An apparatus of this type is disclosed in U.S. Pat. No. 5,200,702.
Nuclear magnetic resonance (NMR) spectroscopy is a powerful method of instrumental analytics. Rotation at the magic angle (magic angle spinning (MAS)), which is approximately 54°, has proven to be a useful method for improving the line sharpness in the obtained NMR spectra, in particular, for semisolid samples (semisolids), e.g. tissue samples. HR pulse programs are therefore also suited to measure high-resolution NMR spectra of inhomogeneous samples.
For a MAS measurement, the sample material is loosely disposed in a so-called rotor and soaked with an NMR solution, e.g. D2O. The rotor is substantially a hollow cylinder that is open on one side. A cap tightly closes the rotor. The cap is substantially rotationally symmetric about an axis. The rotor, which is filled with sample material and closed by a cap, is called sample unit herein. The cap has teeth or blades that can move a sample unit, which is located at a measuring position in an NMR spectrometer, into fast rotation using a gas flow. Rotors and caps are disclosed e.g. in U.S. Pat. No. 5,236,239.
Filling sample material into the rotor, soaking the sample material with NMR solution and closing the rotor with the cap is conventionally effected manually. When the rotor is closed, air and excess NMR solution can escape from the interior of the rotor via a central bore in the cap. The bore in the cap is closed by a screw, which is screwed in manually using a screwdriver when the cap is disposed on the rotor. Manual preparation of the sample units is time-consuming and expensive.
U.S. Pat. No. 5,200,702 discloses automatic supply of the readily prepared sample units to a measuring position of an NMR apparatus and measuring thereof. The sample units are thereby disposed in a stacking tube.
It is the underlying purpose of the present invention to present a MAS-NMR apparatus for preparing sample units, in particular, closing the rotors by caps, in a simple and automated fashion.